The goal of this project is to define immune mechanisms and viral characteristics important in the pathogenesis of Aleutian disease. A lymphocyte proliferative assay was utilized to find mink with advanced Aleutian disease (AD) capable of generating an in vitro T lymphocyte response to viral and specific protein antigens. The assay will allow further study of the relation of T lymphocyte function to viral persistence and hypergammaglobulinemia. Another aspect of the project utilizes monoclonal antibodies to study antigenic differences among ADV isolates. These reagents are also being used as probes to locate viral antigen(s) in tissues of infected mink. Antibodies with three predominant patterns of reactivity have been identified. 1) those that react with viral antigens extracted from tissues of infected mink, 2) those reacting with viral antigens purified from ADV infected cultures, and 3) those reacting with virus from either source. Characterization of the antibodies obtained, and generation of new specificities will continue.